This invention relates to units for generating a predetermined gaseous atmosphere in a container and/or for indicating the presence or absence of the predetermined atmosphere in the container. More particularly, the invention relates to generating and/or indicating units for use by the medical profession in collecting and testing bacterial cultures of the type which remain viable only when in the presence of a particular gaseous environment or atmosphere. For example, bacteria of the anaerobic type require an oxygen-deficient or oxygen-free atmosphere and should be stored and incubated in an environment having little or no oxygen.
A unit which is used for the same general purpose as the unit of the present invention is disclosed in Avery U.S. Pat. No. 4,643,973. That unit comprises a relatively inexpensive bubble pack. One bubble of the pack houses an acid-containing ampoule and also houses tablets which generate hydrogen and carbon dioxide when activated by squeezing the bubble to crush the ampoule and release the acid. Gas flows from the bubble pack into the container to establish an anaerobic atmosphere in the container. The atmosphere of the container communicates with another bubble which houses an ampoule containing a color indicating liquid. When the latter ampoule is crushed, the liquid moistens an absorbent pad which changes colors as the atmosphere of the container changes from aerobic to anaerobic.
The unit disclosed in the aforementioned Avery patent is particularly adapted for use while disposed in a horizontal position and is usually placed along with the cultures or specimens in a sealed transport bag which then is placed in an incubating chamber. While this method of transporting and incubating the specimens is entirely satisfactory, the procedure which is followed in some laboratories is to place the specimens directly in a sealed chamber and to establish the anaerobic atmosphere in the chamber itself.